Background: Measles is a leading cause of childhood morbidity and mortality. Vitamin A deficiency is a recognised risk factor for severe measles. The World Health Organization (WHO) recommends administration of an oral dose of 200,000 IU (or 100,000 IU in infants) of vitamin A per day for two days to children with measles in areas where vitamin A deficiency may be present.
Objectives: The purpose of this review is to determine whether vitamin A when commenced after measles has been diagnosed, is beneficial in preventing mortality, pneumonia and other complications in children.
Search strategy: MEDLINE and the Cochrane Library, Issue 4, 1999 were searched.
Selection criteria: Only randomized controlled trials in which children with measles were given vitamin A or placebo along with standard treatment were considered.
Data collection and analysis: Studies were assessed independently by two reviewers. The analysis of dichotomous outcomes was done using the StatXact software package. Sub-group analyses were done for dose, formulation, age, hospitalisation and pneumonia specific mortality. Weighted mean difference with 95% CI were calculated for continuous outcomes.
Main results: The relative risks (RR) and 95% Confidence Intervals (CI) are based on the estimates from the StatXact software package. There was no significant reduction in mortality in the vitamin A group when all the studies were pooled together (RR 0.60; 95% CI 0.32 to 1.12)(StatXact estimate). There was a 64% reduction in the risk of mortality in children who were given two doses of 200,000 IU of vitamin A (RR=0.36; 95% CI 0.14 to 0.82) as compared to placebo. Two doses of water based vitamin A were associated with a 81% reduction in risk of mortality (RR=0.19; 95% CI 0.02 to 0.85) as compared to 48% seen in two doses of oil based preparation (RR=0.52; 95% CI 0.16 to 1.40). Two doses of oil and water based vitamin A were associated with a 82% reduction in the risk of mortality in children under the age of 2 years (RR=0.18; 95% CI 0.03 to 0.61) and a 67% reduction in the risk of pneumonia specific mortality (RR=0.33; 95% CI 0.08 to 0.92). There was no evidence that vitamin A in a single dose of 200,000 IU was associated with a reduced risk of mortality among children with measles (RR=0.77; 95% CI 0.34 to 1.78). Sub-groups like age, dose, formulation, hospitalisation and case fatality in the study area were highly correlated and there were not enough studies to separate out the individual effects of these factors. There was a 47% reduction in the incidence of croup (RR=0.53; 95% CI 0.29 to 0.89), while there was no significant reduction in the incidence of pneumonia (RR=0.92; 95% CI 0.69 to 1.22) or of diarrhoea (RR=0.80; 95% CI 0.27 to 2.34). Duration of diarrhoea was measured in days and there was a reduction in its duration of almost two days WMD -1.92, 95% CI -3.40 to -0.44. Only one study evaluated otitis media and found a 74% reduction in its incidence (RR=0.26, 95% CI, 0.05 to 0.92). We did not find evidence that a single dose of 200,000 IU of vitamin A per day, given in oil-based formulation in areas with low case fatality, was associated with reduced mortality among children with measles. However, there was evidence that the same dose given for two days was associated with a reduced risk of overall mortality and pneumonia specific mortality.
Reviewer's conclusions: Although we did not find evidence that a single dose of 200,000 IU of vitamin A per day was associated with reduced mortality among children with measles, there was evidence that the same dose given for two days was associated with a reduced risk of overall mortality and pneumonia specific mortality. The effect was greater in children under the age of two years. There were no trials that compared a single dose with two doses, although the precision of the estimates of trials that used a single dose were similar to the trials that used two doses.